My 25 week old baby prefers food over milk?

can anyone please help, my 25 week old baby boy used to love his bottle of milk religiously but since we started weening its a struggle to get him to take it, he will take spooned puree or similar no problem and quite often asks for more (not literally, lol) however when it comes to the bottle he just closes his mouth, or plays with the teat with his tounge, sometimes looking at me giggling (cheeky bugger, haha).does anyone have any suggestions as our health visitor did advise us that he should be taking at least 20oz of milk every day, we are managing to get some milk into him by hiding it into his food but we can not seem to meet the guidelines.